Electrically conductive polymers have applications in a wide range of commercial fields such as electromagnetic interference (EMI) shielding, electrostatic dissipation, electrostatic painting and re-chargeable batteries.
In general, materials can be divided into three groups regarding their electrical conductivity δ: insulators (δ<10−7 S/m), semi-conductors (δ=10−7−105 S/m) and conductors (δ>105 S/m). For polymers, typical conductivity values range from 10−15 S/m up to 10−12 S/m. Carbon fillers can have conductivities in the range of 104 S/m up to 107 S/m.
A non-conducting polymer can gain electrical conductivity by incorporation of highly conductive carbon fillers such as graphite and carbon nanotubes into polymer matrixes.
However, carbon fillers are known to be very difficult to uniformly disperse in polymer composites due to their poor compatibility with polymers. This problem is more severe when inert thermoplastic polymers such as polypropylene (PP) are used.
Surface modification of the fillers, commonly employed to improve compatibility of the filler with the polymer matrix, may adversely affect the intrinsic electrical and thermal properties of the composite.
In summary, there is a need for electrically conductive polymers with high and uniform conductivity. There is also a need for methods for preparation of such composites.